Police in Jersey City are searching for a driver they say struck a bicyclist and fled the scene, leaving a 21-year-old with life-threatening injuries. Police were called just before 5 a.m. Saturday for an injured bicyclist near the area of of Garfield Avenue, Gates Avenue and Seaview Avenue, Hudson County Prosecutor Esther Suarez said. Responding officers found a 21-year-old Bayonne resident with life-threatening injuries. But the striking vehicle did not remain at the scene, authorities said. The victim was transported to Jersey City Medical where he is in critical, but stable condition, Suar…